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Electroluminescence enhancement in ultraviolet organic light‐emitting diode with graded hole‐injection and ‐transporting structure
Author(s) -
Zhang Xiaowen,
Mo Bingjie,
You Fengjiao,
Zhou Xiujuan,
Liu Liming,
Wang Honghang,
Wei Bin
Publication year - 2015
Publication title -
physica status solidi (rrl) – rapid research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.786
H-Index - 68
eISSN - 1862-6270
pISSN - 1862-6254
DOI - 10.1002/pssr.201510086
Subject(s) - electroluminescence , oled , ultraviolet , materials science , quantum efficiency , optoelectronics , diode , biphenyl , benzidine , wavelength , light emitting diode , chemistry , nanotechnology , biochemistry , layer (electronics) , organic chemistry
Electroluminescent intensity and external quantum efficiency (EQE) in ultraviolet organic light‐emitting diodes (UV OLEDs) have been remarkably enhanced by using a graded hole‐injection and ‐transporting (HIT) structure of MoO 3 / N , N ′‐bis(naphthalen‐1‐yl)‐ N , N ′‐bis(phenyl)‐benzidine/MoO 3 /4,4′‐bis(carbazol‐9‐yl)biphenyl (CBP). The graded‐HIT based UV OLED shows superior short‐wavelength emis‐ sion with spectral peak of ∼410 nm, maximum electroluminescent intensity of 2.2 mW/cm 2 at 215 mA/cm 2 and an EQE of 0.72% at 5.5 mA/cm 2 . Impedance spectroscopy is employed to clarify the enhanced hole‐injection and ‐transporting capacity of the graded‐HIT structure. Our results provide a simple and effective approach for constructing efficient UV OLEDs. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim)